1. Field of the Invention
The invention relates to a novel construction of drive disks for cable drives and the like, in particular hoists, for improved power transmission.
Main fields of application of the invention are                hoist drive disks for multiple cable operation,        drive disks for selectively operable in a single cable mode under lifting loads, such as, for instance,        cable driven lifting platforms (for instance façade maintenance devices, building scaffolds);        cable driven vehicles for stationary cable structures (suspension brides, cable suspended roofs, cable cranes, cable cars);        selective cable car drives;        selective chair lift drive;        endless lifting winches for any applications.        
A further field of application of the invention are mechanical endless conveyors operating on the traction principle and which satisfy the preconditions of magnetic materials.
The state of the art relating to lift drive disks is characterized by arrangements, the technical realizations of which is based upon Coulomb's law as applied to friction utilizing a homogeneous groove.
2. The Prior Art
Arrangements are known from the claimed field of application of mining shaft conveyors which, while they increase the driving capacity of the cable-drive disk system by groove inserts of different but soft materials, are unsuited for operating in hoists. About eight decades ago, consideration was given in the mining industry to improving the power transmission by the use of electromagnets.
In this connection, the relevant (German) patent document DE 34 67 27 C discloses the groove of the drive disk wherein the load bearing member is received, to consist of segments structured as pole pieces of an array of electromagnets of alternating polarity the flux path of which between adjacent poles extends through the load bearing member.
In connection with line hauling systems of cable laying ships U.S. Pat. No. 3,512,757 discloses the application of magnets in the cable sheaves of winches. In those cases, conventional magnets used which require significant space and added technical complexity and which, therefor, can be used only in single cable operations of large dimensions.
German patent specification DE 33 12 522 A1 discloses a drive disk for particular use in mining, in which in the grooves of the disk rim there is inserted a lining structured as flexible elastic ring having lining elements affixed thereto.
In German patent specification DE 36 26 045 A1, too, there is described a drive disk for mining applications in which along the circular groove of the rim there is arranged a freely movable coating. The coating consists of two layers, i.e. an upper layer of a strip of elastic material and a layer of subdivided into sections connected to each other and in direct contact with the rim. The mentioned sections in this case consist of a (plain) bearing material.
The subject of German patent specification DE 39 23 192 A1 is a drive disk especially for single cable conveyance in mining provided with a drive disk rim in the groove of which coating inserts are arranged at random with a gap between them. At both their ends, the V-shaped coating inserts are provided, in the direction of movement of the drive disk, with penetrating bores through which a pulling member is fed which is circumscribing the groove.
German patent DE 1,202,587 B describes a reinforcement for use in cable and drive disks for mining applications in which lining materials of a light metal, a hard polymer or the like is affixed to the base body of the of the drive disks and the coefficient of friction and wear resistance of the lining are increased.
German patent DE 1,120,702 B describes a specific lining material for drive disks for shaft conveyors in the mining industry which consists of a specific cast alloy G Al Si. The lining blocks are alternatingly installed on the circumference of the drive disk with lining blocks of thermoplastic polymers or thermoplastic-like polymers.
With prior art inserts in the grooves of drive disk rims known It has been possible to improve wear and frictional behavior of drive disks used in the mining industry. The requisite structural arrangements are complex. In the context of large ratios between the diameter of drive disks and the diameter of cables—greater than about 40—corresponding applications are conceivable in hoist structures as well. The trend toward light structures will lead to ratios of diameters for hoists into the range of 20 to 30. Increased pressure strains and searing stresses—resulting from uneven cable forces—cause the hitherto known insert materials to fail. In single cable operations, the utilization of force fields to increase the driving capacity is known from the mining field and from hauling winches. However, the arrangements are structurally complex, require large space and increase the systems technology.